Water activity-moisture content relationship as a predictive indicator for control of spoilage in commercial pet diet components

Water activity-moisture regressions were determined over practically applicable ranges for several commercial pet diet components and maximum moisture contents critical for stability determined. These latter correspond to aW = 0.60, below which spoilage by microorganisms and mites would not be expected to be a problem. Confirmation of this critical maximum aW level was gained by spoilage of a diet with aW of 0.615 under ambient conditions, but only after 5–6 months.